1. Field of the Invention
The present invention relates to a heat exchanger, in particular, which can suitably regulate the quantity of heat exchange medium fed into tubes to adjust heat exchange performance according to cooling and heating load. More particularly, the heat exchanger of the present invention can selectively regulate or open/close the flow of heat exchange medium therein to control heating or cooling capability, uniformly distribute heat exchange medium through the same, and uniformly maintain the quantity and flow rate of heat exchange medium flowing toward the tubes, thereby preventing lateral temperature difference as well as improving heat exchange performance.
2. Background of the Related Art
As well known in the art, an air conditioning system includes a cooling system and a heating system. In the cooling system, heat exchange medium discharged by the actuation of a compressor circulates through a condenser, a receiver driver, an expansion valve and an evaporator while cooling the vehicle interior through heat exchange in the evaporator. The heating system introduces heat exchange medium (engine cooling water) into a heater core in order to heat the vehicle interior through the heat exchange with the heater core.
The condenser, the evaporator and the heater core are a heat exchanger for performing heat exchange with heat exchange medium. The heat exchanger is fed with heat exchange medium, performs heat exchange with it at a suitable temperature, and then circulates heat exchange medium.
As shown in FIG. 1, a conventional heat exchanger includes a plurality of tubes 5 arranged at a specific interval and having both ends fixed to upper and lower headers 1 and 3, upper and lower tanks 7 and 9 coupled with the upper and lower headers 1 and 3, respectively, to form passages communicating with the ends of the respective tubes 5 and heat radiation fins 11 placed between adjacent ones of the respective tubes to increase heat radiation surface.
When the conventional heat exchanger of the above structure is mounted on an air conditioning system, in particular, to a vehicle air conditioning system, heat exchange medium fed into passages formed by the upper tank 7 and the upper header 1 flow through the first half of the tubes 5 at one side, which are divided by baffles, to perform heat exchange with the ambient air. Then, heat exchange medium U-turns at passages formed by the lower tank 9 and the lower header 3 to flow through the second half of the tubes at the other side to perform heat exchange again, and then discharges through the passages formed by the upper tank 7 and the upper header 1.
In the conventional heat exchanger performing heat exchange as above, since heat exchange medium (vehicle cooling water) is fed regardless of heating or cooling load, additional control means is needed to selectively control heat exchange ability according to heating or cooling load. For example, in the case where the heat exchanger is used as a heater core of a vehicle, the number of rotation of a blower is adjusted or a door is installed in the front of the heat exchanger to adjust air volume, thereby adjusting the heat exchange ability of the heat exchanger. However, since the above scheme of controlling the heat exchange ability through the adjustment of air volume requires an additional apparatus, there is a problem in that control is not reliable.
An approach for solving the above problem is disclosed in Korea Patent No.170234, which is previously filed by the assignee and properly registered. This document proposes a heat exchanger as shown in FIGS. 2 and 3, which includes tubes 5 arranged at an equal interval and having both ends fixed to upper and lower headers 1 and 3, division supplying means 13 connected to the upper header 1 for feeding heat exchange medium to specific ones of the tubes 5 and a lower tank 9 connected to the lower header 3 to communicate with ends of the respective tubes 5.
The division supplying means 13 includes a plurality of communication passages 15 connected with top ends of the tubes 5 coupled with the upper header 1, a body 17 having a cylindrical heat exchange medium-dividing section 19 with inlet sides of the passages 15 being formed in a specific angle range, at least one heat exchange medium-inlet pipe 21 installed to communicate with the heat exchange medium-dividing section 19 in the body 17, a rotary member 23 rotatably mounted on the heat exchange medium-dividing section 19, and having a rotary shaft 25 and cutoff blades 27 mounted on the rotary shaft 25 for selectively closing the inlets of the communication passages 15, and a cover 29 for supporting the rotary shaft 25 and closing the heat exchange medium-dividing section 19.
In this state, heat exchange medium is fed via the heat exchange medium-inlet pipe 21 and the rotary member 23 rotatably mounted on the heat exchange medium-dividing section 19 is rotated according to the load applied to the heat exchanger in order to perform heat exchange with heat exchange medium by using the heat exchanger. Then, the cutoff blades 27 selectively open/close the inlets of the communication passages 15 in response to the rotation of the rotary member 23 to feed heat exchange medium to some or all of the tubes 5.
In the case where the inlets of the communication passages 15 are provided at both sides, the cutoff blades 27 installed at both sides of the rotary member 23 simultaneously open both ends of the tubes 5 to feed heat exchange medium into some of the tubes 5 and the quantity of heat exchange medium can be adjusted in response to the rotation of the rotary member 23 so that the heat exchange ability of the heat exchanger is selectively adjusted.
Heat exchange medium can be selectively fed into the respective tubes 5 of the heat exchanger to selectively adjust the performance of the tubes 5, thereby easily coping with heating or cooling load.
Although the foregoing heat exchanger has an advantage in that it can selectively adjust the quantity of heat exchange medium, there are problems in that heat exchange medium guided by the cutoff blades 27 of the rotary member 23 is excessively crowded in one row of the tubes to lower the mixing ability of heat exchange medium as well as cause a lateral temperature difference to the heat exchanger. Furthermore, in such heat exchanger system, it is not easy to selectively change a supplying order and position of heat exchange medium that is fed to the tubes.